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4.0

Jun 29, 2018
06/18

by
J. Squire; E. Quataert; A. A. Schekochihin

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It is shown that low-collisionality plasmas cannot support linearly polarized shear-Alfv\'en fluctuations above a critical amplitude $\delta B_{\perp}/B_{0} \sim \beta^{\,-1/2}$, where $\beta$ is the ratio of thermal to magnetic pressure. Above this cutoff, a developing fluctuation will generate a pressure anisotropy that is sufficient to destabilize itself through the parallel firehose instability. This causes the wave frequency to approach zero, interrupting the fluctuation before any...

Topics: Space Physics, Cosmology and Nongalactic Astrophysics, Physics, Astrophysics, High Energy...

Source: http://arxiv.org/abs/1605.02759

71
71

Sep 21, 2013
09/13

by
J. Squire; H. Qin; W. M. Tang; C. Chandre

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We present a new variational principle for the gyrokinetic system, similar to the Maxwell-Vlasov action presented in Ref. 1. The variational principle is in the Eulerian frame and based on constrained variations of the phase space fluid velocity and particle distribution function. Using a Legendre transform, we explicitly derive the field theoretic Hamiltonian structure of the system. This is carried out with a modified Dirac theory of constraints, which is used to construct meaningful brackets...

Source: http://arxiv.org/abs/1301.6066v2

2
2.0

Jun 30, 2018
06/18

by
F. I. Parra; I. Calvo; J. W. Burby; J. Squire; H. Qin

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The difference between the guiding center phase-space Lagrangians derived in [J.W. Burby, J. Squire, and H. Qin, Phys. Plasmas {\bf 20}, 072105 (2013)] and [F.I. Parra, and I. Calvo, Plasma Phys. Control. Fusion {\bf 53}, 045001 (2011)] is due to a different definition of the guiding center coordinates. In this brief communication the difference between the guiding center coordinates is calculated explicitly.

Topics: Physics, Plasma Physics

Source: http://arxiv.org/abs/1407.6694